diff --git a/goal_src/levels/finalboss/robotboss.gc b/goal_src/levels/finalboss/robotboss.gc
index a9b74eb269..24f30fa182 100644
--- a/goal_src/levels/finalboss/robotboss.gc
+++ b/goal_src/levels/finalboss/robotboss.gc
@@ -1038,7 +1038,8 @@
          (send-event (ppointer->process (-> self parent)) 'flash 255.0)
          (send-event (ppointer->process gp-1) 'anim-mode 'play1)
          (send-event (ppointer->process gp-1) 'rot-quat (-> self root-override quat))
-         (send-event (ppointer->process gp-1) 'art-joint-anim "robotboss-yelloweco-yellow-last-hit")
+         ;; the zero passed here was missing in the original game, but is a bug that causes undefined behavior
+         (send-event (ppointer->process gp-1) 'art-joint-anim "robotboss-yelloweco-yellow-last-hit" 0)
          )
        )
       ((and (> (-> self hits-to-go) 0) (-> self took-hit))
@@ -1636,7 +1637,8 @@
          (send-event (ppointer->process (-> self parent)) 'flash 255.0)
          (send-event (ppointer->process gp-1) 'anim-mode 'play1)
          (send-event (ppointer->process gp-1) 'rot-quat (-> self root-override quat))
-         (send-event (ppointer->process gp-1) 'art-joint-anim "robotboss-redeco-red-last-hit")
+         ;; the zero passed here was missing in the original game, but is a bug that causes undefined behavior
+         (send-event (ppointer->process gp-1) 'art-joint-anim "robotboss-redeco-red-last-hit" 0)
          )
        )
       ((and (> (-> self hits-to-go) 0) (-> self took-hit))
@@ -2609,7 +2611,8 @@
          (send-event (ppointer->process (-> self parent)) 'flash 255.0)
          (send-event (ppointer->process gp-2) 'anim-mode 'play1)
          (send-event (ppointer->process gp-2) 'rot-quat (-> self root-override quat))
-         (send-event (ppointer->process gp-2) 'art-joint-anim "robotboss-blueeco-blue-last-hit")
+         ;; the zero passed here was missing in the original game, but is a bug that causes undefined behavior
+         (send-event (ppointer->process gp-2) 'art-joint-anim "robotboss-blueeco-blue-last-hit" 0)
          )
        )
       ((-> self took-hit)